1. Field of the Invention
The present invention relates to semiconductor equipment, and more especially, to a pipe union structure connection between fluid channel.
2. Description of the Prior Art
In the semiconductor industry, there usually takes a lot of processes to fabricate a chip. Some of these processes, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and plasma etching (dry etching), need to process a gas, or vapor reaction, and therefore, need a fluid delivery system to deliver the reactive gas and/or precursor material into the processing chamber.
FIG. 1 depicts concisely a portion of a gas delivery system used to bring plasma gas into a wafer process chamber 10 in a photoresist stripping system, wherein the photoresist on the wafer 20 is stripped by plasma etching. In this system, the original gases are brought into a plasma tube 30 through the bubbler 32, and converted into plasma with some reactions such as ionization reaction by using electrode 34 or the like. Once the plasma is generated, the plasma gases are introduced from the plasma tube 30 into the wafer process chamber 10 through the plasma transition passage 36. In the wafer process chamber 10, the photoresist stripping process is carried out by reactive ion etching (RIE). The plasma gases are drawn downward through a gas distribution plate 40 to the surface of the wafer 20, and then the post-reaction gases are exhausted through exhaust passage 50 by an exhaust pump 60.
In general, the conduit of the gas delivery system are not built as an integral object, but built with several discrete parts connected in turn for adapting to the configuration of the system. FIG. 2 illustrates a conventional connecting pipe union structure used in the delivery passage between two discrete conduits such as the plasma tube 30 and the plasma transition passage 36 shown in FIG. 1. The gas in the conduit is flowing from the first pipe 102 to the second pipe 104 as indicated by the arrow 106. Typically, an O-ring 108 is used to seal between the two pipes and prevent leakage or contamination of gas, as well as prevent loss of proper chamber pressure.
A flow-guiding pipe 110 extends from the outlet of the first pipe 102 to the inlet of the second pipe 104. The flow-guiding pipe 110 is disposed to avoid turbulence of the gas flow around the outlet of the first pipe 102, and prevent seal damage by deleterious gas. To realize such a function, the flow-guiding pipe 110 must be disposed with a certain length extending into the first pipe 102.
However, the gas delivery system is not a totally stationary system. A pump used in the system as shown in FIG. 1 must be applied (not shown in this figure). When the pump is running and the gas flowing in the conduits, the conduits will shake, and the two pipes 102 and 104 will move relative to each other. These two pipes 102 and 104 will be bent with the O-ring seal 108 as the fulcrum. The dash lines in FIG. 2 represents a possible position of the second pipe 104 when the shake occurs. In this situation, the distance between the outlet of the flow-guiding pipe 110 and the inner wall of the second conduit pipe 104 varies as the vibration occurs (and almost touch each other as shown in the figure). If the two pipes shake violently, the amplitude of the vibration becomes large, and the flow-guiding pipe 110 will tend to grind, scratch or collide the inner wall of the second pipe 104.
Generally, the conduits of the delivery system are made of materials such as quartz, for withstanding various aggressive gases. When the grind or scratch happens, there could generate particles that will contaminate the plasma gases and then consequently the wafer positioned downstream from the two pipes 102 and 104. Extremely, the collision could cause one or both of the pipes to crack or being broken.